The present invention relates generally to the field of sheet folding machines, and more particularly to a sheet folding machine in which envelopes can be fed into the folding machine along the same feed path as that for sheets, but will be diverted away from the buckle chutes and fed directly to an inserting machine.
Sheet folding machines have long been well known and have enjoyed great commercial success in a variety of document processing applications, particularly those associated with the preparation of mail in which one or a plurality of sheets are folded in a variety of configurations before being inserted into envelopes in an envelope inserting machine. Briefly, folding machines of this character comprise one or a pair of buckle chutes and a plurality of sets of feeding and folding rollers. In a typical arrangement, sheets are fed into the folding mechanism and directed into a first buckle chute by a first pair of feeding rollers until the lead edge of the sheet strikes a stop, after which the portion of the sheet adjacent to the entrance of the buckle chute buckles to form a new lead edge, which then passes through the next pair of feeding rollers which creases the new lead edge, thereby forming a first fold in the sheet. The new lead edge is then directed into a second buckle chute until it strikes a stop, which causes the portion of the sheet adjacent to the entrance of the second buckle chute to buckle and form still another new lead edge, and this new lead edge then passes through still another pair of feeding rollers which again creases the lead edge, thereby forming a second fold in the sheet. The tri-folded sheet is then fed through a discharge path from the folding machine.
Significant developments in recent years in high speed, automated document processing technology have resulted in various types of document processing systems and apparatus which utilize the above described functions of folding machines in combination with printing machines and envelope inserting machines for the purpose of simplifying the process of printing documents and envelopes at the same time, folding the documents and inserting designated documents into designated envelopes. For example, in one system developed by the assignee of this application, a form letter is to be sent to a large number of addressees, but each form letter is personalized by being addressed to an individual whose name and address is in a computer data base. A computer printer, preferably a laser printer in order to obtain optimum print quality, prints a letter with a name and address on a letter head, a large quantity of which is stored in a suitable feeder for the computer printer. Depending on the configuration of the document processing apparatus, either the same or another printer prints the same name and address on an envelope, a large quantity of which is stored in another suitable feeder for whichever printer prints on the envelopes. Both the letters and the envelopes are fed toward the folding machine, the letter being fed along one path which passes through the folding machine, the envelope being fed along another path which bypasses the folding machine and leads directly to the inserting machine. After folding, the letter is fed into the inserting machine and is inserted into the envelope, either by itself or with other insert material, depending on the configuration of the entire document processing apparatus.
Despite the fact that commercially available document processing apparatus for performing a process as just described has been well received, there are a number of problems inherent in the operation of the available apparatus which contribute to high purchase cost, mechanical complexity and limited operating speed, all of which impede the further commercial success of such apparatus. One of these problems is that if one printer is used for both letters and envelopes, the envelopes must be fed through the printer short edge first because most currently available laser printers are either incapable of printing along a wide enough range to print a letter on a letter head and also a return address on an envelope, the latter being well outside of the left margin of the letter being printed by the computer printer. On the other hand, if a wide enough printer is used for both printing tasks, it is very costly and therefor undesirable from a commercial standpoint. In the first situation, since the envelope must be fed into the inserting mechanism long edge first in order for the letter to be inserted, some type of envelope turning mechanism must be provided to turn the envelope through a 90.degree. angle before the envelope can be fed into the inserting mechanism. And in both situations, it is necessary to have separate feed mechanisms and feed paths for the letter and the envelope since the letter must go through the folding machine, but the envelope must bypass the folding machine and proceed directly to the inserting machine. It should be apparent that both the turning mechanism and the separate feeding mechanisms add cost, complexity and limited speed of operation to the processing apparatus.
Alternatively, if two printers are used, one for the letter and another for the envelopes, and if they are both laser printers, a very substantially cost factor is added to the cost of the processing apparatus due to the relatively high cost of good quality, high speed laser printers. And the envelope turning device may still be required.
In a still further alternative, an ink jet printer is substituted for the second laser printer that prints the address and return address on the envelopes, thereby substantially reducing the cost of the second printer, since ink jet printers by and large are considerably less costly than laser printers, and the same quality of print as that desired for the letters is not necessary for the envelopes. Also, the necessity for a turning device is eliminated because the ink jet printer is printing only on the envelope, and it can be configured to print with the envelope traveling with the long edge first However, this introduces still another problem, which is that ink jet printers produce a wet document, thereby preventing the document from being handled in the area of the image until the ink is thoroughly dry in order to prevent the image from being smeared. In order to overcome this problem, it is necessary to provide some type of mechanism that will provide a drying station for the envelopes, typically in the form of a feeding and storage mechanism mounted adjacent the output end of the ink jet printer which will move a plurality of printed envelopes slowly through the drying station and then into the inserting mechanism. This technique, however, introduces two problems, one being the necessity of providing an additional mechanical mechanism, the cost of which offsets, to some extent, the savings realized from changing the second printer from laser to ink jet and eliminating the turning mechanism. The other is that the software control for printing the letters and the envelopes becomes more complicated because instead of simply printing the letters and envelopes in synchronism and feeding both to the inserting mechanism in succession, either a plurality of letters corresponding to the number of envelopes printed and stored in the drying mechanism must be printed and accumulated until the envelope for a designated letter reaches the inserting mechanism, or the letters must be printed out of synchronism with the envelopes, so that, for example, the letter for the first envelope is not printed until all of the envelopes normally stored in the drying mechanism have been printed and the first envelope printed reaches the inserting location.
Thus, it is seen that virtually regardless of the configuration of the document processing apparatus for the particular application under consideration, whether it involves a single printer, for which inexpensive technology is not readily available, or two printers using readily available technology, there are significant problems of one nature or another that prevent a document processing apparatus from being designed and marketed that would effectively take advantage of commercially available document processing components. There is, therefore, a need for a document processing apparatus in which a single laser printer can be utilized for printing both a letter and an envelope in synchronism, printing on the envelope with the long edge leading, feeding both the letter and the envelope, with the long edge leading, along the same feed path by the same feeding mechanism directly from the printer to the folding machine, and causing the envelope to bypass the folding mechanism of the folding machine and move directly therethrough to the inserting machine